偵測約瑟夫森結內的量子能階

Abstract

我們以SQUID當作可調控的電磁環境，探討Small Josephson Junction在不同環境下的I-V特性。觀察到當Cooper Pair於Small Junction兩端的能量差等同於SQUID的能階差時，有額外的穿隧電流出現，此現象可以P(E)理論描述之。此外，SQUID的IC隨外加磁場強度的改變能夠定量地表示，而IC與SQUID能階差的關係也和理論相符。

Using SQUIDs as a tunable electromagnetic environment, we discussed the I-V characteristic of a small Josephson junction in different environments. An additional tunneling current was observed while the energy difference of a Cooper pair tunneling through the small Josephson junction matched the level spacing of SQUIDs. This could be described using the P(E) theory. Furthermore, the measured Ic of the SQUID versus the external magnetic field could be described quantitatively; and experimental results of the IC and the level spacing of the SQUID were in an agreement with theories.